For the purpose of self health management or the like, it is a common practice to grasp one's own amount of exercise using a pedometer. In many conventional pedometers, in order to count the number of steps accurately, because of their structures, restrictions exist regarding the mounting position or mounting direction of main units. In recent years, however, in order to further improve usability, body-movement detecting apparatuses in which it is possible to set a mounting position and mounting direction freely are proposed. Among them, a method and apparatus for performing posture estimation using a multi-axis acceleration sensor and performing body-movement detection using the same sensor have been proposed. This is advantageous in that implementation at an inexpensive cost is possible compared with a method of using an angle sensor or the like for posture estimation.
For example, Japanese Unexamined Patent Application Publication No. 2004-141669 discloses a method in which an acceleration is detected by a plurality of body-movement sensors having mutually different detecting directions, an operation axis is determined/selected by analyzing signal patterns of the individual sensors, and walking detection is performed by signal analysis of the operation axis. Furthermore, Japanese Unexamined Patent Application Publication No. 2005-140533 discloses a method in which an acceleration sensor having mutually orthogonal two axes or three axes is mounted, an exercise direction of body movement is estimated from a combined vector of sensor signals of individual axes, and body movement is detected by analyzing signal components in the estimated exercise direction.